Discarded hypodermic syringes present a serious health hazard. It is not unusual for people to be accidentally pricked by the needle of the syringe after use, and so become infected with a disease which has been transmitted from the person to whom the shot was originally administered. For example, personnel cleaning up hospital spaces or doctors' offices frequently must pick up numerous such syringes after use, and it is very easy to be accidentally pricked or stuck by the needle when doing this. Furthermore, used hypodermic syringes are frequently disposed of in plastic garbage bags, and these are readily pierced by the needles so that these are exposed and can easily prick a person who is handling the garbage bags. Also, municipal garbage is frequently dumped at sea, and there have been cases where syringes have washed up on the beach, where they may be stepped on by barefoot strollers. The seriousness of this problem has been heightened by the spread of the Acquired immune Deficiency Syndrome (AIDS) virus. Not only are diseases such as this spread by the accidental pricking of persons after the syringe has been used, but some persons, notably habitual drug abusers, frequently re-use syringes, without taking the necessary steps to ensure their sterility.
Some attempts have been made to eliminate the problems of re-use and accidental injury from used hypodermic syringes. Some syringes have needles which unscrew from the barrel of the syringe after use, but this is inconvenient, and the loose needles continue to present a hazard. Also, devices have been provided which cut or snap the metal needle off from the plastic body of the syringe, both to prevent its re-use, and also to retain the severed needle in a suitable, relatively thick-walled disposal container. While this provides a relatively satisfactory solution for some facilities, it is not without its drawbacks. For example, hospitals and many doctors' offices have a great many treatment rooms, and it is simply not practical to install a needle clipping device in each of these rooms, for the relatively occasional use which it will receive. More seriously, paramedics and other emergency response personnel who must administer injections at an accident or other emergency scene obviously cannot be burdened with carrying an additional piece of equipment in the form of a needle clipper, and, in any event, they typically do not have time to use such device; this problem is seriously aggravated at many emergency sites, such as automobile accidents, where the paramedic often must work in a confined space or lie on the ground in close proximity with the used hypodermic syringes, and so be at increased risk of being pricked by one of these. A similar situation is faced by military medical personnel in combat situations, and also in military field hospitals.
Accordingly, there exists a need for a hypodermic syringe which provides for protection against injury due to accidental pricking by the point of the used needle, which also prevents reuse of the syringe, without requiring a separate of equipment for doing this. Furthermore, there is a need for a hypodermic syringe having such provisions which is both inexpensive to manufacture and simple to operate.